The present invention generally relates to corrosion inhibitors and, more particularly, to inkjet printing formulations which contain corrosion inhibitors and methods of making the same.
Inkjet printing is a nonimpact printing process in which droplets of ink are deposited on a print medium. Substantial developments have been made in the field of electronic printing technology, leading to the existence of a wide variety of highly efficient printing systems that are capable of dispensing ink in a rapid and accurate manner. One such system is a thermal inkjet printer that utilizes ink cartridges. Thermal inkjet print cartridges operate by rapidly heating a small volume of ink to cause the ink to vaporize and be ejected through one of a plurality of orifices so as to print a dot of ink on a recording medium, such as a sheet of paper. Typically, the orifices are arranged in one or more linear arrays in a nozzle plate. The properly sequenced ejection of ink from each orifice causes characters or other images to be printed upon the paper as the printhead is moved across the paper.
These and other inkjet printing techniques typically impose rigid requirements on the ink compositions. To be suitable for use as a jet ink, the compositions must meet particular requirements. In general, a successful ink set for color inkjet printing should have good crusting resistance, good stability, proper viscosity, proper surface tension, good color-to-color bleed alleviation, rapid dry time, no negative reaction with the vehicle, consumer-safety, good permanence (e.g., smearfastness, lighffastness, waterfastness), and low strike-through. Further, the ink must be quick drying and smear resistant and capable of passing through the inkjet nozzle without clogging. The ink should also permit rapid cleanup of the machine components with minimum effort. When placed into a thermal inkjet system, the ink set should also be kogation resistant and have stable drop ejection performance (e.g. little or no drop velocity degradation over time).
Corrosion of metal parts is a problem presented in many industrial fields, including the field of inkjet printing. Difficulties have been encountered in the development of inkjet printing formulations which do not cause or promote undue corrosion of metal parts of the inkjet printing apparatus that come into contact with the printing ink. Although ink compositions are required to have certain characteristics, few ink compositions possess all the aforementioned properties, since an improvement in one property often results in the degradation of another property. Thus, many inks commercially used represent a compromise in an attempt to achieve an ink evidencing at least an adequate response in each of the performance attributes, such as waterfastness and optical density. One such compromise has resulted in the addition of acids to provide particular attributes to the ink composition, such as bleed control. However, the addition of acid to these inks, along with other ink components, such as surfactants, colorants, and electrolytes, render the inks corrosive towards steel.
In response to this problem, substantial time and effort has been expended formulating specific inkjet formulations that are acceptable from the standpoint of minimizing metal corrosion. Thus, a need exists for corrosion inhibitors that can be incorporated into inkjet formulations to reduce corrosion of metal parts which come into contact with the inkjet formulations. Such inhibitors at the same time should not adversely affect the previously described, desirable properties of the ink compositions.
For general applications in fields not requiring such stringent control of physicochemical parameters, many compositions, including acetylenic alcohols and derivatives thereof, have been employed as corrosion inhibitors. For example, U.S. Pat. No. 5,084,210 describes a corrosion inhibitor containing an acetylenic alcohol that is used in connection with a chlorine dioxide process for controlling biomass and cleaning water injection wells and oil producing wells. U.S. Pat. No. 4,557,838 describes inhibition of metal corrosion caused by aqueous acid solutions by admixing a synergistic additive consisting of a heterocyclic nitrogen compound or alkylamine with an acetylenic alcohol and dialkythiourea to the aqueous acid solution. U.S. Pat. No. 3,816,322 describes dispersing a compound containing a heterocyclic amine, an acetylenic alcohol, and an ionizable iodine containing compound into an aqueous acidic solution containing a polyhydric compound in order to protect iron surfaces against corrosion by the aqueous acidic solution. U.S. Pat. Nos. 6,284,153; 6,086,786; 6,007,885; 5,993,688; and 5,985,169 describe oxygen-scavenging compositions containing alkyl alcohols for inhibition of corrosion in metal storage containers.
Despite all of the foregoing uses of a variety of alcohols, in corrosion inhibiting formulations, either directly, or as salts, derivatives, or complexes, use of acetylenic alcohols in inkjet formulations to inhibit or eliminate corrosion of metal inkjet printer parts that come in contact with such inkjet formulations have not been disclosed. In view of the shortcomings in the art, there is a need for inkjet ink compositions including corrosion inhibitors and methods of reducing or eliminating metal corrosiveness of inkjet ink compositions.
In accordance with the present invention, acetylinic alcohols are incorporated into inkjet printing formulations at a level sufficient to inhibit corrosion of metal (e.g., steel) placed in contact with the ink formulation, while having essentially no effect upon the physicochemical properties of the inkjet formulation. The ability to add such acetylenic alcohols in sufficient quantity to inhibit corrosion, while not significantly affecting the physicochemical properties of the inkjet formulation permits previously formulated jet ink compositions to be rendered corrosion resistant, without requiring complete reformulation of the ink composition.
The present invention additionally provides improved inkjet ink compositions having a sufficient amount of an acetylenic alcohol incorporated therein to reduce the corrosiveness of the ink without adversely affecting the printing characteristics of the ink composition.
The inkjet ink compositions of the invention include a carrier, a colorant that is soluble or dispersable in said carrier, and a sufficient quantity of at least one acetylenic alcohol to reduce the corrosiveness of said ink composition to metal placed in contact with said ink composition. In a particular embodiment of the invention, the inkjet composition includes at least one acetylenic alcohol that contains a terminal acetylene and an xcex1-hydroxy group. In yet another embodiment, the acetylenic alcohol is preferably selected from the group consisting of propargyl alcohol, methyl butynol, 3,5-dimethyl-1-hexyne-3-ol, 1-hexyne-3-ol, 5-methyl-1-hexyne-3-ol, 1-octyn-3-ol 1-phenyl-2-propyn-1-ol, 1-ethynyl-cyclopentan-1-ol, and 1-ethynyl-cyclohexan-1-ol. The acetylenic alcohol preferably comprises from about 500 ppm to about 0.5% total weight of said ink composition. A method for reducing corrosiveness of an inkjet ink composition includes adding to said inkjet ink composition a sufficient quantity of at least one acetylenic alcohol, as previously described, to reduce the corrosiveness of said ink composition to metal placed in contact with said ink composition.